I've done a search, but I can only find lots of green poo stories.
My 17 month old ds had a bowel explosion twice on Sunday night (usually a once in the morning sort of chap), both were noisy, smelly and very pale (think ready brek but with sulphur smell). Since then at least 3 a day all enormous, right down the leg, fill your slippers jobs. He has an incredible pain threshold (which I've posted about before) but he does seem to feel discomfort immediately before (which given he can fall off a slide and crack his head open, or cut 4 teeth at once and sleep through the night, is enough to worry me).
He is breastfed, so I am happy to just keep rehydrating him and see what happens, but how long before I consider ringing the doctor? He seems like a quieter version of himself and has got tired easily these last couple of days.